U.S. Pat. No. 4,170,063 to Bettcher (herein “the '063 patent”) discloses a rotary knife having a removable blade. The '063 patent is assigned to Bettcher Industries, the assignee of the present invention. The '063 patent discloses a hand knife having a ring-like rotary blade that is rotated by a motor in a handle that extends normal to an axis of rotation of the blade. The blade of the knife is rotatably supported in a housing that surrounds a part of the blade. The blade can be removed for sharpening or replacement of the blade. Other representative United States patents relating to rotary knives that are assigned to the assignee of the present invention are U.S. Pat. No. 4,439,924, U.S. Pat. No. 4,516,323, and U.S. Pat. No. 4,509,261.
Pneumatic meat trimming knives having an air powered motor with a user-operated control valve for governing the flow of operating air to the motor are known. The pneumatic knives include rotating, or oscillating blades that are driven by air motors. Conventionally these tools' are connected to a source of high pressure air via a flexible conduit. Their operation is controlled by a user-actuated valve that is opened and closed to start and stop the drive motor.